//可以给fiber添加一个副作用标识符，表示此fiber对应的DOM节点需要进行何种操作
export const NoFlags = 0b000000000000000000 //0 啥都不干
export const Placement = 0b000000000000000010 //2 插入
export const Update = 0b000000000000000100 //4 更新
export const PlacementAndUpdate = 0b000000000000000110 //6 超级更新
export const Deletion = 0b000000000000001000 //8 删除
